1. Field of the Invention
The present invention relates to a high-frequency module suitable for use in, for example, a voltage controlled oscillator or a transmitting and receiving unit used in a cellular phone.
2. Description of the Related Art
A related high-frequency module has a wiring pattern and an electrical part. The wiring pattern is formed of a thick film and is provided on the surface of an insulating substrate that is formed by stacking materials in layers and between the layers forming the insulating substrate. The electrical part comprising a resistor and/or a capacitor is formed of a thick film and is provided on the surface of the insulating substrate and between the layers forming the insulating substrate.
An integrated circuit (IC) chip, formed of a semiconductor material, is mounted to the wiring pattern, formed on the surface of the insulating substrate, so as to be exposed at and protrude from the surface of the insulating substrate.
Since the electrical part of the related high-frequency module is formed of a thick film, it has large variations in thickness and poor performance.
In addition, since the IC chip is mounted to the surface of the insulating substrate, the related high-frequency module has increased thickness. Therefore, it cannot be made thin, and its IC chip breaks because external force tends to be exerted upon the IC chip in the exposed state.
Accordingly, it is an object of the present invention to provide a thin, high-performance high-frequency module having an IC chip with little breakage.
To this end, according to the present invention, there is provided a high-frequency module comprising an insulating substrate comprising a plurality of ceramic thin plates stacked in layers, and an insulating layer disposed on a top surface of the insulating substrate. In the high-frequency module, a thin-film circuit is disposed on a top surface of the insulating layer, and comprises a wiring pattern and an electrical part comprising a resistor and/or a capacitor. The wiring pattern is formed of a thin film. The electrical part is connected to the wiring pattern and is formed of a thin film. The insulating substrate has at least one conductive member disposed between the layers forming the insulating substrate, a first connection conductor and a second connection conductor disposed in the thickness direction, and an electrode disposed on a side surface of the insulating substrate with the electrode being connected to the conductive member. The first connection conductor is connected to the wiring pattern, and the second connection conductor is connected to an integrated circuit chip accommodated inside the insulating substrate and to the wiring pattern.
Although not exclusive, the ceramic thin plates forming the insulating substrate may be capable of being baked at a low temperature, and the insulating layer may be formed of glass or polyimide.
Although not exclusive, a top end of each of the connection conductors may have a protrusion which protrudes from the top surface of the insulating substrate, and each protrusion may be flush with or may protrude from the surface of the insulating layer, so that the wiring pattern is in electrical conduction with each protrusion.
Although not exclusive, a sealant, formed of an insulating material, may fill a recess of the insulating substrate accommodating the integrated circuit chip.
Although not exclusive, the integrated circuit chip may be formed of a bare chip.